Laser imaging systems are commonly used to produce photographic images from digital image data generated by magnetic resonance (MR), computed tomography (CT), or other types of scanners. Systems of this type typically include a continuous tone laser imager for exposing the image on photothermographic film, a thermal film processor for developing the film through the application of heat, and an image management subsystem for coordinating the operation of the laser imager and the thermal film processor. The light sensitive photothermographic film can include a polymer or paper base coated with an emulsion of dry silver or other heat sensitive material.
One known type of thermal processor for use in developing the photographic film utilizes a thermal drum processor. Once the film has been subjected to photo stimulation by optical means such as laser light, it is fed into the thermal drum processor for development.
The thermal drum processor includes a rotating drum cylinder which is heated to develop the film. For example, the drum surface may be heated utilizing a heating element coupled to the internal surface of the drum, or alternatively, other methods may be used such as the rotating drum cylinder being located within an oven-like enclosure.
The film is engaged by the rotating drum and heated for a desired period or "dwell time" to allow for development of the images on the photothermographic film. Mechanisms may be employed for holding the film against the rotating drum surface, such as the use of a plurality of rollers positioned about the drum surface.
In known systems the installation of the plurality of necessary rollers in the drum has proven to be a complex operation requiring a number of exacting mechanical operations and requiring a multiplicity of mechanical parts that are required to be aligned and adjusted as part of the installation process. Presently, the rollers in the film thermal processing drum are mounted to a die cast metal housing where the rollers are inserted into slots in the housing. Each roller is individually secured to the housing using metal fasteners which are required to be screwed down on both the inside and outside of the housing.
In light of the known drawbacks of present laser image thermal processing devices, it is desirable to have a roller mounting assembly for use in a thermal drum processor system which allows for quicker installation of rollers about the drum and also minimizes the complexity of the assembly by reducing the number of parts necessary for its installation, maintenance and use. Further, it is desirable to have a roller mounting assembly which allows for easy access and removal of the rollers for maintenance and cleaning.
Further, the temperature of the processing drum is a critical element in the carrying out of the thermal processing process. In particular, it is the temperature of the surface of the drum that is a critical parameter to be measured and controlled for uniform and controlled development of images on the film. In existing systems, one known place for the measurement of the temperature of the drum is accomplished by mounting a resistance thermal device (RTD) element to the internal surface of the drum. An internally mounted temperature sensing system has several disadvantages: it does not give a true, more direct reading of the drum surface temperature; it requires more costly assembly; and measurement of the RTD state must pass through a slip-ring connection or requires that the control and measurement hardware be positioned on the rotating drum. It is desirable to provide a mechanism for measuring the surface temperature of the drum directly and accurately for improved control of the thermal processing operation, while reducing overall complexity and cost of the temperature sensing system.